Predicting the translational-rotational coupling factor for polyatomic molecules from the self-diffusion coefficient

Abstract

The translational-rotational coupling factor, or roughness factor, introduced by Chandler, has been evaluated for twelve substances in the liquid range (between the triple and critical points) by means of a reduced number of self-diffusion data. The influence of experimental data, simulation procedures, different choices for the hard sphere diameter, and the introduction of the modified Enskog theory have been included in this study. The results support the validity of the model.

Mutual diffusion coefficient models for polymer-solvent systems based on the Chapman-Enskog theory

“…Accordingly, interest in the Chapman-Enskog transport theory has markedly increased due mainly to its well-based formalism, making it the backbone of transport treatment. In previous works (Dymond, 1985;Speedy, 1987;Heyes, 1988;Erkey et al, 1990;Erpenbeck andWood, 1991, Harris, 1992;Amoros, 1994;Ruckenstein and Liu, 1997;Liu et al, 1998;Yu and Gao, 1999), some theoretical details and shortcomings, implicit in the original Enskog models for dense fluids (Chapman and Cowling, 1970) have been discussed and some changes have been proposed with the aim of making it possible to calculate diffusion coefficients for more complex fluids in wider ranges of temperatures and compositions. Nevertheless, to date the diffusion studies involving macromolecules show that applicability of the original Enskog model is still limited.…”